Golf club, jetdrv driver for increased distance and accuracy

ABSTRACT

A golf club, a driver, designed to provide an inprovement in the accuracy of ball control as club head speeds are increased from 100 miles per hour to the level of a semipro at 120 miles per hour. Most forces on the club head increase as the square of the velocity, representing a forty four percent increase. A detailed analysis has been made of forces generated during the collision of the ball and club head and their effect on trajectory of the ball. The design proposed greatly reduces the aerodynamic drag of the clubhead, increases the allowable tolerance to angular misalignment of the club striking face from two degrees to ten degrees and reduces the torque that twists the club head causing an angular misalignment prior to contact with the ball.

U.S. PATENT DOCUMENTS

3,595,577 July 1971 Hodge 3,625,518 December 1971 Solheim 3,941,390March 1976 Hussey 4,471,961 September 1984 Masghati 5,354,059 October1994 Stuff 5,366,223 November 1994 Werner 5,511,786 April 1996 Antonious5,735,754 April 1998 Antonious 5,971,868 October 1999 Kosmatka 5,997,413December 1999 Wood 6,139,445 October 2000 Werner 6,190,267 February 2001Marlowe 6,312,534 November 2001 Grensing 6,319,437 November 2001 Elsner6,371,868 April 2002 Galloway 6,402,636 June 2002 Chang 6,478,692November 2002 Kosmatka

BACKGROUND OF THE INVENTION

Golf has become a very popular sport for both the amateur and theprofessional resulting in rapid improvements in courses, hazzards, clubsand balls. The two clubs which account for the most strokes on the scorecard are the driver and the putter. The driver is responsible forcovering the the majority of the yardage on most courses, andconsequently is responsible for getting its owner into the mostdifficult to impossible lies. Recent trend in driver design has been toget more distance by increasing head speed. This improved range has beenaccomplished by the combination of a reducion in clubhead weight,increased shaft length to make the increased club head speed possible.Clubhead speeds of 120 miles per hour could result in 260 yard drives,however, if the clubhead is only two degrees off normal when strikingthe ball, this will cause the drive to be off the aiming point by thisangular error of at least nine yards. The induced side spin on ball willadd a hook or slice to this error. For accuracy, it is essential thatthe player develop his swing to repeatedly align the velocity vector atthe clubhead center of gravity pointed directly at the desired location.For the weekend golfer to improve his driving from a clubhead velocityof 100 MPH to 120 MPH he has to contend with a 144 percent increases indrag, centrifugal force and inertia force. It is not practical to swingthe same club at the higher speed without introducing an uncontrollableslice.

The proposed driver design is capable of obtaining higher swing speedsby the reduction in the weight and a more accurate control of theclubhead twist by reducing the unbalanced moments that result from thesum of the aerodynamic drag inertia loading. The decrease in thependulum action by reducing its offset moment will ensure more hets onthe sweet spot, resulting in obtaining added distance with an increasedaccuracy.

Various efforts have been made to increase the clubhead speed bycreating a controlled, favorable turbulance which reduces the area ofreduced pressure at the rear of the club thereby reducing theaerodynamic drag as shown in U.S. Pat. Nos. 3,468,544, 4,828,265,5,511,786, and 5,735,754 by Antonious.

A clubhead design has been proposed to have been multi-angularlystreamlined to reduce aerodynamic drag when swung through the entire 120degrees prior to impact in U.S. Pat. No. 5,997,413. Aerodynamic dragvaries as the square of the speed and is only significant at the latterpart of the swing. Efforts have been made to eliminate the twisting orturning of a golf club head during the golf swing in U.S. Pat. Nos.3,595,577 and 3,941,390 by Hodge and Woodridge. This has beenaccomplished in their proposed designs by the addition of a large hoselto control the center of gravity or the installation of high-densitymaterials.

A golf club for minimizing spin of the golf ball and reducing hooks andslices by the addition of a lubricant to the striking face of the clubin U.S. Pat. No. 6,402,636. The present study shows the spin is tointroduce to the ball by a rolling action with friction not required. Aproposed Pat. No. 5,366,223, addresses the persistent problem of thefailure to hit the golf ball fully on the strike face by analyzing thelocation of the 11 hits by each of 28 golfers. Study had shown there wasa pronounced elliptical distribution pattern of impacts over that manyswings, they called this pattern the “hit pattern”. The driver faceswere then recommended to be oriented to take advantage of the shape ofthe hit pattern. The present study shows on FIG. 5 that this movement isdue to the centrifuge force causing a pendulum motion about the wristcock axis. Reducing the offcet center of gravity will eliminate most ofthis movement.

In U.S. Pat. No. 6,190,267 this invention claims to be able to controlthe location of the center of percussion to within 0.500 inch of theouter toe end portion of the clubhead. This claim is impossible sincethe center of precussion is close to the club center of gravity. Theinventors error is in the selection of the shaft centerline as the pivotpoint in the analysis rather than at the wrist-cock-axis.

In U.S. Pat. No. 6,139,445 this invention claims to have face surfaceshapes which are designed to reduce the scatter of the points where aball stops after a hit. This patent differs from the proposed patentthat claims that a greater tolerance is introduced for an angularlymisaligned clubhead at point of contact with the ball and accounting forthe extensive distortion of the ball during impact.

In U.S. Pat. No. 6,371,868 this invention is a golf club having aninterior hosel that is disposed inward from a striking plate to allowfor compliance of the striking plate during impact with the golf ball.It claims to have a striking plate or face with a coefficient ofrestitution approaching 0.93. This coefficient of restitution representsa seven percent loss of velocity and a 14 percent loss in kinetic energyresulting from the flexible striking plate. This patent differs from theproposed patent which has an airfoil shaped hosel for a significantreduction in aerodynamic drag of the round shaft. The proposed designhas a crowned, thick striking face giving a coefficient of restitutionof nearly 1.0. To eliminate the danger associated with the failure ofthe dissimilar material bonded joint of shaft to clubhead a roll pin isused for an additional mechanical attachment.

In U.S. Pat. No. 6,478,692 this invention proposes a compliant golf clubhead to permit a more efficient impact between a golf ball and the golfhead. It is stated that material and geometry constraints of a strikingplate of the golf club head can reduce energy losses caused by largestrain and strain rate values of the golf ball. The inventor presents anextensive static analysis of a simulated elliptical striking plate,varying thickness and materials with contact force as a variable. Theselected force used in the comparison is F=2500 lbs. This is nearly halfof the contact force required to accelerate the ball to the observedspeed that has been measured experimentally. Any deflection of thestriking plate will reduce the kinetic energy in the ball rather thanreduce the energy losses as stated. AU analysis was conductedconsidering contact at the “sweet spot”, the deflection during an offcenter hit will introduce an error in the directional trajectory of theball. The proposed patent is of aluminum with a minum thickness locallyof 0.25 inch as well as a significantly smaller striking face. Thedesign is based on controlling the deflective shape of the ball bycontact with a rigid contoured striking face.

SUMMARY OF THE INVENTION

The present invention relates to a golf club, the driver, that has beendesigned to provide the golfer with a club capable of producing anincreased accuracy as he attains greater distance with the increasedclubhead speed. There is a tremendous amount of information published onhow to grip and swing a golf club.

In Jack Nicklaus's book “Golf My Way” published by Simon and Schuster hesays “The overall swings of golfers like Ben Hogan, Bobby Jones andmyself may appear different, but, because basically there is only onecorrect way to deliver the club to the ball, they look almost identicalat impact”. “The three elements of power: 1, clubhead speed; 2, on-linedelivery of clubhead relative to target line; 3, square impacting ofclubface on ball. Distance is diminshed anytime any of the these threeelements is missing”.

The second extremely valuable book “Search for Perfect Swing” byAlastair Cochran and John Stubbs, published by Triumph Books. This bookis a condensed account of a wide and fascinating exploration of golf,made possible by the imagination and support of Sir Aynsly Bridgland andthe Golf Society of Great Britian (G.S.G.B.).

The third most helpful book “The Physics of Golf”, by Theodore P.Jorgensen Department of Physics and Astronomy University of Nebraska.This book provides an excellent quantitave comparison of an analyticaltreatment of the golf club swing and corrolates these results withexperimental measured data. Additionally a computer program is providedin Qbasic by The American Institute of Physics. This program wasmodified by the inventor to include the effects of the aerodynamic dragon the clubhead and shaft. Results of this analysis were used to studythe clubhead-to-ball transfer of energy and how it can be controlled toimprove strike accuracy. The ball is assumed to be a spherical springand the clubhead a ridge anvil to deform the ball in a desirable manner,controlling ball spin and direction. Kinetic energy transferred fromclubhead to ball is proportional to the square of the club velocity atimpact and directly as the ratio of the mass of the clubhead to the massof the ball. Clubhead mass and aerodynamic drag is reduced to provide ahigher velocity for the same energy input by the golfer. The center ofgravity of the clubhead is more closely alligned with the shaft axis toensure contact alignment between center of gravity of the clubhead andthe ball, namely the sweet spot.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 give the results of a detailed analysis of club-ball interchangeof energy during collison of a seven ounce clubhead at a velocity of165.8 ft/sec with a ball at rest accelerating it to 231.2 ft/sec in0.000038 sec. Clubhead speed at end of contact was 102.8 ft/sec. Maximumforce of contact is is 4403 lbs occuring 0.000010 sec after contact.During this contact period the ball rolls up the face of the club with aroll radius decreasing as the contact force increases. A driver with aface angle of 11 degrees has been computed to give the ball a rotationof 66 rev/sec and leave the club face at an angle of 8.77 degrees and231.2 ft/sec.

FIG. 2A and FIG. 2D are the front and rear views of the proposed JETDRVgolf club. FIG. 2B is the side view of the Cross Section B-B showing thestriking face section and the hosel shaft interface. FIG. 2C is the topview of Cross Section A-A showing striking face detail and airflowpassages.

FIG. 3A illustrates the airflow patterns around a conventional driverclub head, in computing the aerodynamic drag it is considered a bluntbody, 24. A blunt body with a low aspect ratio will have all of the airflowing around the exterior of the body, resulting in separation withthe resulting turbulent vortex flow producing low pressures at the rearof the body. Seperation occurs when the surface air film can no longerfollow the surface contour of the club head. The central streamline atthe face of the club comes to rest with a resulting increase inpressure, while the seperated air at the rear of the club is at agreatly reduced pressure. The air drag on the club head is then equal tothe difference in the integrated force of pressure times area on theleading face of the club minus the integral of the pressure times areaof the trailing surface of the club. This resulted in a drag force of7.45 lbs at 165.8 ft/sec. This force will vary for different swingspeeds as the square of the club velocity at impact.

FIG. 3B illustrates the airflow patterns around the JETDRV driver when anacelle, 20, is introduced around the club head, 22. The air within thecapture area of the nacelle is diffused within the nacelle by thecontrolled area distribution, slowing the flow of air as it approachesthe discharge nozzle. Since the amount of air leaving through the nozzleequals the amount of air entering its exit velocity will be equal to theratio of the capture area to the discharge nozzle area times the inletvelocity, giving a discharge velocity of 732.4 ft/sec, close to sonicvelocity. The drag coefficient on this type of flow is proportional tothe product of the surface wetted area times the surface skin friction.The calculated drag at 165.8 ft/sec club head velocity was 0.0243 lbs.

FIG. 4A illustrates the shaft twisting torque generated by thecombination of the aerodynamic drag and the inertia force as a result ofthe club head acceleration up to the 165.8 ft/sec, multiplied by theoffset 1.008 inch from the center of gravity and the center of pressuregiving 30.91 in lbs for the conventional club. This is compared with theJETDRV driver in FIG. 4B that gives a twist torque of 7.42 in lbs. Thistorque tends to open the club face, causing a misaligned shot andprobably an uncontrollable slice. This results in a 4 to 1 improvementin the twist torque.

FIG. 5 illustrates the pendulum action driven by the centrifugal forceof 75.54 lbs acting on the club head center of gravity with the offsetdistance of 1.008 in. for the conventional driver. The club will pivotabout the wrist cock axis, as shown in the deflected position when thecenter of gravity is aligned with the shaft centerline. This offsetdistance has been reduced to 0.388 in. for the JETDRV driver. Thecentrifugal and inertia forces are related to the clubhead weight andthe offset distance is critical to controlling the accuracy of thedrive.

FIG. 6 illustrates the inital impact point of the clubface on the ballfor an 11 degree angle of the driver clubface. This contact is initally0.171 inch below the center of gravity of the ball, dropping to 0.138inch at the maximum ball compressed deflection of 0.2448 inch resultingin a maximum contact force of 4403 lbs. This offset produces a torsionalmoment on the ball, causing it to roll up the face of the club. Becauseof the deflection of the ball this rolling radius changes from 0.84 inchinitally to 0.57 inch at its maximum displacement. This rolling actionaccelerates the ball to 66 rps at separation with the ball leaving theclub face at 231.2 ft/sec inclined to 8.77 degrees.

FIG. 7 illustrates that with a club head misalignment of as much as 10degrees at contact with the ball it still does not produce a significantmoment on the ball, which causes the ball to rotate horizontally,resulting in a slice.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the golf club proposed is illustrated in FIG. 2A,front view, and FIG. 2D, rear view, with the top view of the crosssection FIG. 2C, and cross section of the side view FIG. 2B. Theclubhead 20, with the striking face 25 has a plurality of score lines23. An elliptical shaped nacelle 10, attached to the clubhead by foursupport struts of airfoil cross section 40. The leading edge of thenacelle has an elliptical cross section 55 for low drag in guiding theair past the nacelle leading edge. The club shaft 50 is attached to thehosel 35, the support strut 40 and the internal cylindrical shroud 35.The shaft 50, can be a hollow steel shaft or solid graphite filamentthat is bonded to the aluminum clubhead. For safety in reduncy, a rollpin or steel rivit 45 is inserted through the shaft attaching it to thecylindrical shroud 35. Air enters the passage 28 between the nacelle 10and the clubhead 20 where the flow area change diffuses the flowreducing its velocity thereby increasing to over twice the ambientpressure. The air is then expanded as it passes through the exit nozzle30 at near sonic velocity. The top of the club 60 is of ellipsoidalshape to present a low drag profile for the club as it rotates through a90 degree angle as it travles from the top of the swing to the contactwith the ball. FIG. 4B illustrates three recessed triangles 70, thelarger central triangle designates the location of the sweet spot andthe outer two represent a measured distance on the contoured strikingface used for controlled slices and hooks.

1. A golf club, driver, is designed with a nacelle surrounding theclubhead. This nacelle is designed to capture a stream tube of air thatenters the club head, the internal air passage shape provides anincreasing diffusion volume, reducing the air velocity, therebyincreasing its pressure. The air is then expanded by discharging it, atnear sonic velocity, through the nozzle at the rear of the club. The ramdrag of the air entering the club is balanced by the jet thrustresulting from the change in momentum. The drag is then limited to skinfriction on surface area exposed to air flow. This drag is far less thanthe blunt body drag of a conventional clubhead.
 2. A hosel of anaerodynamic airfoil design to reduce the drag.
 3. Four symetricalairfoil shaped struts supporting the nacelle and capable of transmittingthe inertia load of the nacelle to the striking head of the club. Onestrut is alligned with the hosel as an extention to attach the clubshaft to the clubhead.
 4. Clubhead with a external shape designed toprovide the area distribution within the nacelle for diffusing the airas it passes through the club. The clubhead is hollow to control theweight and the center of gravity location relative to the shaftcenterline.
 5. The striking face of the clubhead is thick and contouredto make it rigid and give it a high natural frequency on impact with theball. The deformation shape of the ball is controlled by the strikingface acting as an anvil to deform the ball. Spin and spin direction andforce to accelerate the ball is controlled by the shape of the strikingsurface. The magnitude of the force is dependent on the mass of theclubhead and its velocity at time of impact.
 6. The contour of thestriking face of the clubhead is designed to increase the tolerance toangular misalingment from about two degrees in the conventional driverto ten degrees for the proposed driver.
 7. Three recessed triangles onthe top surface of the clubhead define the location of the sweet spotand a measured distance on the contoured striking face that can be usedby the highly proficient golfer for making controlled hooks and slices.They can also be used to compensate for high crosswinds giving a reduceddrag and improved distances.
 8. A roll pin is added to provide amechanical attachment as backup to the cement bond of the dissimilarmeterials in the shaft and clubhead.